Valve gear

Abstract

Provided is a valve gear which achieves a reduced size and is capable of changing the valve opening timing of an engine valve and changing the length of the valve opening period thereof. A valve gear is provided with: a rotatable first camshaft; a first cam piece that is relatively unrotatably provided on the first camshaft; a second camshaft that is included in the first camshaft and coaxially rotatable; a second cam piece that is relatively unrotatably provided on the second camshaft; a housing; a first vane rotor that is relatively rotatable with respect to the housing; and a second vane rotor that is relatively rotatable with respect to the housing and the first vane rotor The first vane rotor is relatively unrotatably coupled to the second camshaft, and the second vane rotor is relatively rotatably coupled to the first camshaft.

The invention claimed is: 
     
       1. A valve gear driving an engine valve of an internal combustion engine, comprising:
 a first camshaft rotatable around a rotation axis; 
 a first cam piece driving the engine valve, the first cam piece being prohibited to rotate relative to the first camshaft; 
 a second camshaft disposed inside the first camshaft, the second camshaft being rotatable around the rotation axis; 
 a second cam piece driving the engine valve, the second cam piece being prohibited to rotate relative to the second camshaft; 
 a housing; 
 a first vane rotor housed in the housing, the first vane rotor being rotatable relative to the housing; and 
 a second vane rotor housed in the housing, the second vane rotor being rotatable relative to the housing and the first vane rotor, 
 wherein the first vane rotor is connected to one of the first camshaft and the second camshaft, being prohibited to rotate relative to the one, 
 and wherein the second vane rotor is connected to the other one of the first camshaft and the second camshaft, being rotatable relative to the other one, the valve gear, further comprising: 
 a first connecting member switching between a permission state and a prohibition state, wherein relative rotation between the first vane rotor and the second vane rotor or relative rotation between the housing and one of the first vane rotor and the second vane rotor is permitted in the permission state; and prohibited in the prohibition state, and 
 a second connecting member switching between a permission state and a prohibition state, wherein relative rotation between the housing and the other one of the first vane rotor and the second vane rotor is permitted in the permission state and prohibited in the prohibition state. 
 
     
     
       2. The valve gear according to  claim 1 , wherein the first vane rotor and the second vane rotor are lined up along the rotation axis direction. 
     
     
       3. The valve gear according to  claim 2 , wherein the first connecting member is switching between a permission state and a prohibition state, wherein relative rotation between the first vane rotor and the second vane rotor is permitted in the permission state and prohibited in the prohibition state; and
 the second connecting member is switching between a permission state and a prohibition state, wherein relative rotation between the housing and the second vane rotor is permitted in the permission state and prohibited in the prohibition state. 
 
     
     
       4. The valve gear according to  claim 3 ,
 wherein the first connecting member includes: 
 a first spring housed in the first vane rotor; and 
 a first pin housed in the first vane rotor and entering the second connecting member by an urging force of the first spring, 
 and wherein the second connecting member includes: 
 a second spring housed in the second vane rotor; and 
 a second pin housed in the second vane rotor and entering the housing by an urging force of the second spring. 
 
     
     
       5. The valve gear according to  claim 1 , wherein the second vane rotor is arranged on a radially inner side of the first vane rotor. 
     
     
       6. The valve gear according to  claim 5 , wherein the first connecting member is switching between a permission state and a prohibition state, wherein the permission state permits and the prohibition state prohibits relative rotation between the first vane rotor and the housing; and
 the second connecting member is switching between a permission state and a prohibition state, wherein the permission state permits and the prohibition state prohibits relative rotation between the housing and the second vane rotor. 
 
     
     
       7. The valve gear according to  claim 6 ,
 wherein the first connecting member includes: 
 a first spring housed in the first vane rotor; and 
 a first pin housed in the first vane rotor and entering the housing by an urging force of the first spring, 
 and wherein the second connecting member includes: 
 a second spring housed in the second vane rotor; and 
 a second pin housed in the second vane rotor and entering the housing by an urging force of the second spring. 
 
     
     
       8. The valve gear according to  claim 1 , wherein the first cam piece and the second cam piece drive the same engine valve.